It is worth getting a day ticket, which is valid for travel on all local buses, trams, trains and the Suomenlinna Ferry. The price is €8 and can be purchased from the ticket machine at the tram terminal at the West Harbour Terminal if arriving by Ferry and throughout the city
Places of interest for a day visit
A short walk north from the Market Square is the Helsinki Cathedral. It is set in an impressive open square and the architecture of the cathedral is exceptional. Walks around the coast are generally pleasant and just across to the south east of the Market Square is Upsenski Cathedral (Russian Orthodox). Going west from the Market Square through Espalnade Park brings you to the Stockmann building the Harrods of Helsinki. It's worth checking out the distinctive polygon paving along Keskuskatu between the two Stockmann department stores. Around the far side of the Stockmann building the Three Smiths monument
The Central Railway station has an impressive facade and behind it to it's North East there is a relaxing green park, and beyond that some pleasant riverside views. Helsinki is built mainly on granite. It is worth going underground and exploring. It becomes apparent that it is possible to move almost anywhere in the city centre without the necessity of stepping outside, which is a huge bonus in winter.
Very many Finns speak some English many to a high standard. You can be confident ordering food, asking for directions, etc.